1. Field of the Invention
This invention relates to a method and apparatus for deaerating food in a continuous grinding operation to provide an anaerobic environment in the grinder and thus improve the organoleptic properties of the final ground food products.
2. Description of the Prior Art
In the manufacture of food items such as sausages or other meat products, the ultimate appearance or eye appeal of the products is of paramount importance. In sausages for example made up of ground or comminuted meats, processors go to great lengths to minimize the phenomenon of "smearing", or the loss of particulate identity in the products. By the same token, it is highly desirable to maintain a strong red meat color in many sausage products.
Previously, large batch-type vacuum choppers have been used in the meat industry. In practice, a charge of meat is placed within the tub of such a chopper, and the lid closed; a vacuum is then drawn to remove air, whereupon chopping knives within the tub are activated to cominute the meat. While these types of choppers are known, they are deficient in that they preclude continuous operations; moreover, the meat is necessarily subjected to the effects of air after the chopping step is completed as a result of unloading and subsequent handling.
In addition, many food products are graded or gradable according to bacteria count inasmuch as product quality and shelf life depend largely on the extent to which the bacteria is either killed or its growth prevented or reduced during processing and subsequent to marketing, prior to preparation for consumption. Many harmful microorganisms, especially bacteria, grow most rapidly in the presence of oxygen. Hence, whenever processing includes grinding of meats prior to packaging, the bacterial problem can be reduced quite substantially if air is removed before the product is introduced into the grinder.
U.S. Pat. No. 4,479,614 describes a highly advantageous grinding apparatus especially designed for use with a dual reciprocable piston pump of the type sold by the Marlen Research Corporation of Overland Park, Kans. The grinder device is operated via a separate motor and drive, and is operatively coupled to the pump through a valved conduit assembly. The dual piston Marlen pumps referred to above are designed to deliver a high pressure stream of food or other products, and it has been known in the past to equip such pumps with apertured pistons and air-conveying conduits so as to deaerate successive previously ground product charges prior to pumping. The '614 patent does not, however, suggest or intimate use of a deaerating piston pump in conjunction with a grinding device in order to achieve true continuous vacuum grinding.
Accordingly, there is a real and unsatisfied need in the art for a method and apparatus which permits continuous grinding of meat or other products under anaerobic conditions to improve the appearance and shelf-life qualities of final ground products.